Tail-Recursive `Element.prototype.closest` Polyfill

tail-recursive-closest.js

/*
 * Element.matches()
 * https://developer.mozilla.org/en-US/docs/Web/API/Element/matches
 * The Element.matches() method returns true if the element would be selected
 * by the specified selector string; otherwise, returns false.
 *
 * Prefixed Support: Android 2.2, Internet Explorer 9, Edge 12, Safari 5.0
 * Unprefixed Support: Chrome 34, Firefox 34, Safari 7.1, iOS Safari 8.0
 */

if (!("matches" in Element.prototype)) {
  Element.prototype.matches = Element.prototype.msMatchesSelector
    || Element.prototype.webkitMatchesSelector;
}


/*
 * Element.closest()
 * https://developer.mozilla.org/en-US/docs/Web/API/Element/closest
 * The Element.closest() method returns the closest ancestor of the current
 * element (or the current element itself) which matches the selectors given in
 * parameter. If there isn't such an ancestor, it returns null.
 *
 * Support: Chrome 41, Firefox 35, Safari 9.0
 */

if (!("closest" in Element.prototype)) {
  Element.prototype.closest = function closest(selector) {
    "use strict";
    return (function searchUpTree(selector, element) {
      return element == null
        ? null
        : element.matches(selector)
          ? element
          : searchUpTree(selector, element.parentElement);
    }(selector, this));
  };
}